Definition of Anemia, addisonian

Anemia, addisonian: A blood
disorder caused by a lack of vitamin B12. Patients who
have this disorder do not produce the substance in the
stomach that allows the body to absorb vitamin B12. This
substance is called intrinsic factor (IF).

Addisonian anemia, better known today as pernicious anemia (PA), is characterized by the presence in the blood
of large, immature, nucleated cells (megaloblasts) that are
forerunners of red blood cells. (Red blood cells, when
mature, have no nucleus). It is thus a type of
megaloblastic anemia.

Pernicious anemia (PA) was first described (although not by that
name) in 1855 by the English physician Thomas Addison. He called it
an invariably fatal "idiopathic anemia." The "idiopathic" was
a frank admission that the cause of this illness was wholly
unknown. The name "pernicious anemia" was coined in 1872 by
the German physician Anton Biermer whose description of the
disease was superior to that of Addison. The studies of
George H. Whipple on the effects of feeding liver in anemia
followed by those of George R. Minot and Wm. P. Murphy on
the effects of feeding liver specifically in pernicious
anemia (PA) led to the cure of PA and to their receiving
the Nobel Prize in 1934.

Nowadays PA is an unpernicious anemia. It is simply treated with
vitamin B12. The vitamin B12 has to be administered by injection
(parenterally) because people with PA do not have IF (or an effective
form of IF) and so cannot absorb vitamin B12 taken by mouth.

There is some evidence that PA may be genetic although its
mode of inheritance is poorly documented. There is a
congenital form of PA due to defect of IF that is clearly
inherited as an autosomal recessive trait with the affected
child having received two copies of the gene, one from each
parent. The IF gene itself has been localized to human
chromosome 11.